A shark attack is an attack on a human by a shark. Every year over 70 attacks are reported worldwide. Despite their relative rarity, many people fear shark attacks after occasional serial attacks, such as the Jersey Shore shark attacks of 1916, and horror fiction and films such as the Jaws series. Out of more than 489 shark species, only three are responsible for a double-digit number of fatal, unprovoked attacks on humans: the great white, tiger, and bull.[1] The oceanic whitetip has probably killed many more castaways, but these are not recorded in the statistics.[2]

According to the International Shark Attack File (ISAF), between 1958 and 2016 there were 2,785 confirmed unprovoked shark attacks around the world, of which 439 were fatal.[4]

In 2000, there were 79 shark attacks reported worldwide, 11 of them fatal.[5] In 2005 and 2006 this number decreased to 61 and 62 respectively, while the number of fatalities dropped to only four per year.[5] The 2016 yearly total of 81 shark attacks worldwide was on par with the most recent five-year (2011–2015) average of 82 incidents annually.[6] By contrast, the 98 shark attacks in 2015, was the highest yearly total on record.[6] There were four fatalities worldwide in 2016, which is lower than the average of eight fatalities per year worldwide in the 2011–2015 period and six deaths per annum over the past decade.[6] In 2016 58% of attacks were on surfers.[6]

Despite these reports, however, the actual number of fatal shark attacks worldwide remains uncertain. For the majority of Third World coastal nations, there exists no method of reporting suspected shark attacks; therefore, losses and fatalities near-shore or at sea there often remain unsolved or unpublicized.

Of these attacks, the majority occurred in the United States (53 in 2000, 40 in 2005, and 39 in 2006).[7]The New York Times reported in July 2008 that there had been only one fatal attack in the previous year.[8] On average, there are 16 shark attacks per year in the United States, with one fatality every two years.[9] According to the ISAF, the US states in which the most attacks have occurred are Florida, Hawaii, California, Texas and the Carolinas, though attacks have occurred in almost every coastal state.[10]

Australia has the highest number of fatal shark attacks in the world, with Western Australia recently becoming the deadliest place in the world for shark attacks[11] with total and fatal shark bites growing exponentially over the last 40 years.[12] Since 2000 there have been 16 fatal shark attacks along the West Australian coast[13] with divers now facing odds of one in 16,000 for a fatal shark bite.[12][14]

The location with the most recorded shark attacks is New Smyrna Beach, Florida.[18] Developed nations such as the United States, Australia and, to some extent, South Africa, facilitate more thorough documentation of shark attacks on humans than developing coastal nations. The increased use of technology has enabled Australia and the United States to record more data than other nations, which could somewhat bias the results recorded. In addition to this, individuals and institutions in South Africa, the US and Australia keep a file which is regularly updated by an entire research team, the International Shark Attack File, and the Australian Shark Attack File.

The Florida Museum of Natural History compares these statistics with the much higher rate of deaths from other causes. For example, an average of more than 38 people die annually from lightning strikes in coastal states, while less than 1 person per year is killed by a shark in Florida.[19][20] In the United States, even considering only people who go to beaches, a person's chance of getting attacked by a shark is 1 in 11.5 million, and a person's chance of getting killed by a shark is less than 1 in 264.1 million.

However, in certain situations the risk of a shark attack are higher. For example, in the south west of West Australia the chances of a surfer having a fatal shark bite in winter / spring are 1 in 40,000 and for divers it is 1 in 16,000.[12][14] In comparison to the risk of a serious or fatal cycling accident, this represents 3 times the risk for a surfer and 7 times the risk for a diver.[12]

A blacktip reef shark. In rare circumstances such as bad visibility, blacktips may bite humans, mistaking them for prey. Under normal conditions, however, they are harmless and often even quite shy.

Only a few types of sharks are dangerous to humans. Out of more than 480 shark species, only three are responsible for two-digit numbers of fatal unprovoked attacks on humans: the great white, tiger and bull;[1] however, the oceanic whitetip has probably killed many more castaways which have not been recorded in the statistics.[2] These sharks, being large, powerful predators, may sometimes attack and kill people; however, they have all been filmed in open water by unprotected divers.[21][22] The 2010 French film Oceans shows footage of humans swimming next to sharks in the ocean. It is possible that the sharks are able to sense the presence of unnatural elements on or about the divers, such as polyurethane diving suits and air tanks, which may lead them to accept temporary outsiders as more of a curiosity than prey. Uncostumed humans, however, such as those surfboarding, light snorkeling or swimming, present a much greater area of exposed skin surface to sharks. In addition, the presence of even small traces of blood, recent minor abrasions, cuts, scrapes or bruises, may lead sharks to attack a human in their environment. Sharks seek out prey through electroreception, sensing the electric fields that are generated by all animals due to the activity of their nerves and muscles.

Most of the oceanic whitetip shark's attacks have not been recorded,[2] unlike the other three species mentioned above. Famed oceanographic researcher Jacques Cousteau described the oceanic whitetip as "the most dangerous of all sharks".[23]

Modern-day statistics show the oceanic whitetip shark as seldom being involved in unprovoked attacks. However, there have been a number of attacks involving this species, particularly during World War I and World War II. The oceanic whitetip lives in the open sea and rarely shows up near coasts, where most recorded incidents occur. During the world wars, many ship and aircraft disasters happened in the open ocean, and because of its former abundance, the oceanic whitetip was often the first species on site when such a disaster happened.

Infamous examples of oceanic whitetip attacks include the sinking of the Nova Scotia, a British steamship carrying 1,000 people that was torpedoed by a German submarine on November 18, 1942, near South Africa. Only 192 people survived, with many deaths attributed to the oceanic whitetip shark.[24] The same species is believed to have been responsible for many of the 60–80 or more shark casualties following the torpedoing of the USS Indianapolis on July 30, 1945.[25]

In addition to the four species responsible for a significant number of fatal attacks on humans, a number of other species have attacked humans without being provoked, and have on extremely rare occasions been responsible for a human death. This group includes the shortfin mako, hammerhead, Galapagos, gray reef, blacktip, lemon, silky shark and blue sharks.[1] These sharks are also large, powerful predators which can be provoked simply by being in the water at the wrong time and place, but they are normally considered less dangerous to humans than the previous group.

On the evening of 16 March 2009, a new addition was made to the list of sharks known to have attacked human beings. In a painful but not directly life-threatening incident, a long-distance swimmer crossing the Alenuihaha Channel between the islands of Hawai'i and Maui was attacked by a cookiecutter shark. The two bites, delivered about 15 seconds apart, were not immediately life-threatening.[27]

Shark attack indices use different criteria to determine if an attack was "provoked" or "unprovoked." When considered from the shark's point of view, attacks on humans who are perceived as a threat to the shark or a competitor to its food source are all "provoked" attacks. Neither the International Shark Attack File (ISAF) nor the Global Shark Attack File (GSAF) accord casualties of air/sea disasters "provoked" or "unprovoked" status; these incidents are considered to be a separate category.[28][29] Postmortem scavenging of human remains (typically drowning victims) are also not accorded "provoked" or "unprovoked" status.[29][30] The GSAF categorizes scavenging bites on humans as "questionable incidents."[29] The most common criteria for determining "provoked" and "unprovoked" attacks are discussed below:

The great white shark is the first of only four species of sharks that have been involved in a significant number of fatal unprovoked attacks on humans

Provoked attacks occur when a human touches a shark, pokes it, teases it, spears, hooks or nets it, or otherwise aggravates/provokes the animal in a certain manner. Incidents that occur outside of a shark's natural habitat, e.g., aquariums and research holding-pens, are considered provoked, as are all incidents involving captured sharks. Sometimes humans inadvertently "provoke" an attack, such as when a surfer accidentally hits a shark with a surf board.

Unprovoked attacks are initiated by the shark—they occur in a shark's natural habitat on a live human and without human provocation.[28][29] There are three subcategories of unprovoked attack:

Hit-and-run attack – Usually non-fatal, the shark bites and then leaves; most victims do not see the shark. This is the most common type of attack and typically occurs in the surf zone or in murky water. Most hit-and-run attacks are believed to be the result of mistaken identity.[31]

Sneak attack – The victim will not usually see the shark, and may sustain multiple deep bites. This kind of attack is predatory in nature and is often carried out with the intention of consuming the victim. It is extraordinarily rare for this to occur.

Bump-and-bite attack – The shark circles and bumps the victim before biting. Great whites are known to do this on occasion, referred to as a "test bite", in which the great white is attempting to identify what is being bitten. Repeated bites are not uncommon, depending on the reaction of the victim (thrashing or panicking may lead the shark to believe the victim is prey), and can be severe or fatal. Bump-and-bite attacks are not believed to be the result of mistaken identity.[31]

Large sharks species are apex predators in their environment,[33] and thus have little fear of any creature (other than orcas[34]) with which they cross paths. Like most sophisticated hunters, they are curious when they encounter something unusual in their territories. Lacking any limbs with sensitive digits such as hands or feet, the only way they can explore an object or organism is to bite it; these bites are known as test bites.[35] Generally, shark bites are exploratory, and the animal will swim away after one bite.[35] For example, exploratory bites on surfers are thought to be caused by the shark mistaking the surfer and surfboard for the shape of prey.[36] Nonetheless, a single bite can grievously injure a human if the animal involved is a powerful predator such as a great white or tiger shark.[37]

Feeding is not the reason sharks attack humans. In fact, humans do not provide enough high-fat meat for sharks, which need a lot of energy to power their large, muscular bodies.[36]

A shark will normally make one swift attack and then retreat to wait for the victim to die or weaken from shock and blood loss, before returning to feed. This protects the shark from injury from a wounded and aggressive target; however, it also allows humans time to get out of the water and survive.[38] Shark attacks may also occur due to territorial reasons or as dominance over another shark species, resulting in an attack.[39]

Sharks are equipped with sensory organs called the Ampullae of Lorenzini that detect the electricity generated by muscle movement.[40] The shark's electrical receptors, which pick up movement, detect signals like those emitted from fish wounded, for example, by someone who is spearfishing, leading the shark to attack the person by mistake.[39]George H. Burgess, director of the International Shark Attack File, said the following regarding why people are attacked: "Attacks are basically an odds game based on how many hours you are in the water".[41]

The bull shark is the third in statistics of unprovoked attacks on humans.[30] They are found in freshwater rivers and lakes as well as the ocean.[42]

In Australia and South Africa shark nets are used to reduce the risk of shark attack. Since 1936 sharks nets have been utilised off Sydney beaches.[43] Nowadays they are employed on both NSW and Queensland beaches; 83 beaches are meshed in Queensland compared with NSW's current 51.[43][44] Since 1952 numerous beaches in South Africa are protected by the KwaZulu-Natal Sharks Board.

Shark nets do not offer complete protection but work on the principle of "fewer sharks, fewer attacks". They reduce occurrence via shark mortality. Reducing the local shark populations is believed to reduce the chance of an attack. Historical shark attack figures suggest that the use of shark nets and drumlines does markedly reduce the incidence of shark attack when implemented on a regular and consistent basis.[45] The downside with shark nets is that they do result in bycatch, including threatened and endangered species.[46]

A drum line is an unmanned aquatic trap used to lure and capture large sharks using baited hooks. They are typically deployed near popular swimming beaches with the intention of reducing the number of sharks in the vicinity and therefore the probability of shark attack. Drum lines were first deployed to protect users of the marine environment from sharks in Queensland, Australia in 1962. During this time, they were just as successful in reducing the frequency of shark attacks as the shark nets[47] More recently, drumlines have also been used with great success in Recife, Brazil where the number of attacks has been shown to have reduced by 97% when the drumlines are deployed.[48] While shark nets and drum lines share the same purpose, drum lines are more effective at targeting the three sharks that are considered most dangerous to swimmers: the bull shark, tiger shark and great white shark.[49]

The effect the media has on the population's view of shark attacks has generally been negative. Starting with the effects generated from news broadcasts, a shark attack is quickly broadcast across the country, particularly if fatal, even though more people die from random occurrences such as lightning strikes than from a shark attack.[55]

In 2010 nine Australian survivors of shark attacks banded together to promote a more positive view of sharks. The survivors made particular note of the role of the media in distorting the fear of sharks.[57] Films such as Jaws were the cause of large-scale hunting and killing of thousands of sharks.[58] There are some television shows, such as the famous Shark Week, that are dedicated to the preservation of these animals.[59] They are able to prove through scientific studies that sharks are not interested in attacking humans and generally mistake humans as prey.

^Rice, Xan (19 July 2011). "Great white shark jumps from sea into research boat". The Guardian. London: Guardian Media Group. Retrieved 20 July 2011. Marine researchers in South Africa had a narrow escape after a three-metre-long great white shark breached the surface of the sea and leaped into their boat, becoming trapped on deck for more than an hour. [...] Enrico Gennari, an expert on great white sharks, [...] said it was almost certainly an accident rather than an attack on the boat.